System and method for post-occlusion surge mitigation

ABSTRACT

According to certain embodiments, a surgical cassette for an ophthalmic surgical system comprises an irrigation conduit that is in fluid communication with a handpiece and carries fluid toward a surgical site. An aspiration conduit is in fluid communication with the handpiece and carries fluid away from the surgical site. An aspiration pump creates a vacuum pressure in the aspiration conduit to draw fluid through the aspiration conduit towards a drain reservoir. A reservoir couples with a pressure-vacuum source to manage the reservoir pressure. A valve is in fluid communication with the aspiration conduit and the reservoir, and provides one or more channels between the aspiration conduit and the reservoir. Each sensor detects a pressure associated with the surgical site. A computer controls the valve in response to the pressure detected by the one or more pressure sensors to mitigate a pressure or volume change.

TECHNICAL FIELD

The present disclosure relates to ophthalmic surgical systems andmethods, and more particularly to systems and methods that mitigatepost-occlusion surges during ophthalmic surgery.

BACKGROUND

Cataract surgery involves removing the cataractous lens and replacingthe lens with an artificial intraocular lens (IOL). The cataractous lensis typically removed by fragmenting the lens and aspirating the lensfragments out of the eye. The lens may be fragmented using, e.g., aphacoemulsification handpiece, a laser handpiece, or other suitablehandpiece. During the procedure, the handpiece fragments the lens(using, e.g., ultrasound vibrations or laser energy), and the fragmentsare aspirated out of the eye through, e.g., a needle. Throughout theprocedure, irrigating fluid is pumped into the eye to maintain anintraocular pressure (TOP) to prevent collapse of the eye.

A common complication during the fragmentation process arises from ablockage, or occlusion, of the needle. As the irrigation fluid andemulsified tissue are aspirated through the hollow cutting needle,pieces of tissue that are larger than the needle's bore may clog thetip. When the tip is clogged, vacuum pressure builds up within the tip.An occlusion break occurs when the clog is removed, e.g., the tissuebreaks free and moves through the needle. When the clog is removed, thevacuum pressure in the anterior chamber suddenly drops, resulting in apost-occlusion surge. In some cases, the post-occlusion surge can causea relatively large quantity of fluid and tissue to be aspirated out ofthe eye too quickly, potentially collapsing the eye and/or tearing thelens capsule.

Various techniques have been designed to mitigate this surge. However,there remains a need for improved ophthalmic systems that mitigatepost-occlusion surges as well as maintain a stable IOP throughoutvarying flow conditions. The present disclosure addresses one or moredeficiencies of the prior art.

BRIEF SUMMARY

In certain embodiments, a surgical cassette for an ophthalmic surgicalsystem comprises: an irrigation conduit, an aspiration conduit, anaspiration pump, a reservoir, a valve, one or more pressure sensors, anda computer. The irrigation conduit is in fluid communication with ahandpiece and carries fluid toward a surgical site. The aspirationconduit is in fluid communication with the handpiece and carries fluidaway from the surgical site. The aspiration pump creates a vacuumpressure in the aspiration conduit to draw fluid through the aspirationconduit towards a drain reservoir. The reservoir holds fluid and coupleswith a pressure-vacuum source to manage the reservoir pressure of thereservoir. The valve is in fluid communication with the aspirationconduit and the reservoir, and provides one or more channels between theaspiration conduit and the reservoir. Each sensor detects a pressureassociated with the surgical site. The computer controls the valve inresponse to the pressure detected by the one or more pressure sensors tomitigate a pressure and/or volume change.

Embodiments may include none, one, some, or all of the followingfeatures:

In certain embodiments, the computer controls the valve to decrease thevacuum pressure in the aspiration conduit when the pressure associatedwith the surgical site is less than a first pressure threshold.

In certain embodiments, the computer controls the valve to decrease thevacuum pressure by controlling the valve to provide the one or morechannels to allow fluid from the reservoir to the aspiration conduit. Incertain cases, the computer controls the valve to provide the one ormore channels by providing a first channel from the reservoir to theaspiration pump or a second channel from the reservoir to an aspirationconnector, the aspiration connector configured to couple to thehandpiece. In other cases, the computer controls the valve to providethe one or more channels by providing a first channel from the reservoirto the aspiration pump and a second channel from the reservoir to anaspiration connector, the aspiration connector configured to couple tothe handpiece.

In certain embodiments, the first pressure threshold may have a value inthe range of 0 to 207 mmHg.

In certain embodiments, a first pressure sensor detects when thepressure associated with the surgical site is less than the firstpressure threshold. In certain cases, the first pressure sensorcomprises an irrigation pressure sensor configured to detect anirrigation pressure within the irrigation conduit. In other cases, thefirst pressure sensor comprises an irrigation pressure sensor configuredto detect an irrigation pressure at the surgical site. In yet othercases, the first pressure sensor comprises a handpiece pressure sensorlocated at the handpiece.

In certain embodiments, the computer controls the valve to decrease thevacuum pressure in the aspiration conduit when the pressure associatedwith the surgical site is less than a first pressure threshold. Incertain cases, the computer controls the valve to cease the decrease ofthe vacuum pressure in the aspiration conduit by controlling the valveto cease allowing the fluid after a predetermined period of time. Inother cases, the computer controls the valve to cease the decrease ofthe vacuum pressure in the aspiration conduit by controlling the valveto cease allowing the fluid when a diverter of the valve reaches aclosing angle.

The computer controls the valve to cease the decrease of the vacuumpressure in the aspiration conduit when the pressure associated with thesurgical site reaches a second pressure threshold by controlling thevalve to cease allowing the fluid. In certain cases, the second pressurethreshold has a value in the range of 0 to 760 mmHg. In certain cases, asecond pressure sensor detects when the pressure associated with thesurgical site reaches the second pressure threshold. The second pressuresensor may comprise an aspiration pressure sensor that detects anaspiration pressure within the aspiration conduit.

In certain embodiments, the surgical cassette further comprises anirrigation pump in fluid communication with the irrigation conduit andthe reservoir. The irrigation pump provides irrigation fluid pressure tothe reservoir.

In certain embodiments, the pressure-vacuum source maintains thereservoir pressure of the reservoir at a specific pressure with a valuein the range of 0 to 500 mmHg.

In certain embodiments, the valve is located at the reservoir.

In certain embodiments, the valve is located along the aspirationconduit and between an aspiration connector and the reservoir. Theaspiration connector can be coupled to the handpiece.

In certain embodiments, a surgical cassette for an ophthalmic surgicalsystem comprises: an irrigation conduit, an aspiration conduit, anaspiration pump, a reservoir, a valve, one or more pressure sensors, anda computer. The irrigation conduit is in fluid communication with ahandpiece and carries fluid toward a surgical site. The aspirationconduit is in fluid communication with the handpiece and carries fluidaway from the surgical site. The aspiration pump creates a vacuumpressure in the aspiration conduit to draw fluid through the aspirationconduit towards a drain reservoir. The reservoir holds fluid and coupleswith a pressure-vacuum source to manage the reservoir pressure of thereservoir. The valve is in fluid communication with the aspirationconduit, and the reservoir, and the aspiration pump, and provides one ormore channels between the aspiration conduit, and the reservoir, and theaspiration pump. Each sensor detects a pressure associated with thesurgical site. The computer controls the valve in response to thepressure detected by the one or more pressure sensors to mitigate apressure and/or volume change.

In certain embodiments, a method for surge mitigation in an ophthalmicsurgical system includes: carrying, by an irrigation conduit, fluidtoward a surgical site, the irrigation conduit in fluid communicationwith a handpiece; carrying, by an aspiration conduit, fluid away fromthe surgical site, the aspiration conduit in fluid communication withthe handpiece; creating, by an aspiration pump, a vacuum pressure in theaspiration conduit to draw fluid through the aspiration conduit towardsa drain reservoir; providing, by a valve, one or more channels betweenthe aspiration conduit and a reservoir, the reservoir configured to becoupled with a pressure-vacuum source to manage a reservoir pressure ofthe reservoir, the valve in fluid communication with the aspirationconduit and the reservoir; detecting, by one or more pressure sensors, apressure associated with the surgical site; and controlling, by acomputer, the valve in response to the pressure detected by the one ormore pressure sensors to mitigate a pressure and/or volume change.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an ophthalmic surgical system that maybe used to perform ophthalmic procedures on an eye;

FIG. 2 is a block diagram of a surgical console of the ophthalmicsurgical system of FIG. 1;

FIG. 3 is a schematic illustrating a fluidics subsystem that may be usedwith the surgical console of FIGS. 1 and 2;

FIGS. 4A through 4F illustrate examples of operations that a valve ofthe fluidics subsystem of FIG. 3 may perform;

FIGS. 5A through 5F illustrate examples of operations a valve that maybe controlled to perform the operations of the valve of FIGS. 4A through4F, respectively;

FIG. 6 illustrates an example of a method that may be used by thefluidics subsystem of FIG. 3 to mitigate a post-occlusion surge; and

FIG. 7 illustrates another example of a method that may be used by thefluidics subsystem of FIG. 3 to mitigate a post-occlusion surge.

DESCRIPTION OF EXAMPLE EMBODIMENTS

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the disclosure is intended. Any alterations and furthermodifications to the described devices, instruments, methods, and anyfurther application of the principles of the present disclosure arefully contemplated as would normally occur to one skilled in the art towhich the disclosure relates. In particular, it is fully contemplatedthat the features, components, and/or steps described with respect toone embodiment may be combined with the features, components, and/orsteps described with respect to other embodiments of the presentdisclosure. For the sake of brevity, however, the numerous iterations ofthese combinations will not be described separately. For simplicity, insome instances the same reference numbers are used throughout thedrawings to refer to the same or like parts.

The present disclosure relates generally to devices, systems, andmethods for performing lens fragmentation procedures. Duringfragmentation, mitigating a post-occlusion surge can be critical to thesuccess of the procedure. The devices, system, and methods disclosedherein include a valve and reservoir for mitigating post-occlusionsurges. When an occlusion break is detected, a valve allows flow fromthe reservoir to increase the fluid volume to decrease the vacuumpressure within the aspiration path connected to a handpiece and pump,thereby reducing or preventing a post-occlusion surge. In such a manner,the valve can mitigate a pressure and/or volume change, which may beexpressed as a pressure or volume change, with an inclusive “or”. Thereservoir may be pressurized to allow for more responsive mitigation.Moreover, the valve may allow flow from the reservoir through one ormore channels. When pressure has sufficiently recovered, the valve maycease decreasing the vacuum pressure.

FIG. 1 illustrates an example of an ophthalmic surgical system 10 thatmay be used to perform ophthalmic procedures on an eye. In theillustrated example, system 10 includes the console 100, a housing 102,a display screen 104, a foot pedal 108, a fluidics subsystem 110, and ahandpiece 112, coupled as shown and described in more detail withreference to FIG. 2.

FIG. 2 is a block diagram of the subsystems of the console 100 ofFIG. 1. The console 100 includes a housing 102, which accommodates acomputer 103 and subsystems 106, 110, 116, and 120 that supportcomponents 108, 112, 109, and 122. A foot pedal subsystem 106 receivesinput from a foot pedal 108. A fluidics subsystem 110 provides fluidcontrol for a handpiece 112, an irrigating cannula 109, and a vitrectomyhandpiece 122. A handpiece subsystem 116 supports the handpiece 112. Forexample, the subsystem 116 may manage ultrasonic oscillation for aphacoemulsification (phaco) handpiece or may provide laser energy to alaser handpiece. A pneumatic vitrectomy cutter subsystem 120 controls avitrectomy handpiece 122. A display screen 104 shows data provided bythe computer 103.

FIG. 3 is a schematic illustrating the fluidics subsystem 110 that maybe used with the surgical console 100 of FIGS. 1 and 2. In general, thecomputer 103 controls parts of the fluidics subsystem 110 to maintain atarget intraocular pressure (IOP) of the eye (which may have a value inthe range of 0 to 110 millimeters of mercury (mmHg)) during a surgicalprocedure. The computer 103 may determine the IOP from measurement of apressure associated with a surgical site of the eye, or the “surgicalsite pressure”. The surgical site pressure is a pressure (notnecessarily measured at the surgical site) that indicates theintraocular pressure (IOP) of the eye. For example, the fluidicssubsystem 110 may include a sensor at or inside of the eye that candirectly measure the IOP of the eye. The fluidics subsystem 110 may thenreceive a measurement of the surgical site pressure from the sensor. Asanother example, the irrigation pressure measured at an irrigationconduit and/or the aspiration pressure measured at an aspiration conduitmay indicate the IOP. The surgical site pressure may not be the same asthe IOP, but may correspond to the IOP in that a higher surgical sitepressure indicates a higher IOP and a lower surgical site pressureindicates a lower IOP. The fluidics subsystem 110 has a variety ofsensors 330, 365 (described below) that can measure the surgical sitepressure.

The surgical site pressure may have a target range that corresponds tothe target IOP of the eye. For example, the irrigation pressure may havea target range of 0 to 110 mmHg (e.g., a value in the range of 0 to 30,30 to 70, or 70 to 110 mmHg), or the aspiration pressure may have atarget range of −760 to 110 mmHg (e.g., a value in the range of −760 to−300, −300 to −100, or −100 to 110 mmHg). If the computer 103 determinesthe surgical site pressure is outside of the target range, indicatingthat the IOP is also outside of the target range, the computer 103controls the fluidics subsystem 110 to bring the pressure back to thetarget range. For example, to mitigate a post-occlusion surge, a firstpressure threshold may indicate when the surgical site pressure is,e.g., below a first threshold in response to an occlusion breakage, anda second pressure threshold may indicate when the surgical site pressureis acceptable, indicating the surgical site pressure has recovered. Incertain embodiments, the computer 103 controls a valve to decrease thevacuum pressure in an aspiration conduit when the surgical site pressureis less than the first pressure threshold, and controls the valve tocease decreasing the vacuum pressure when the surgical site pressure thereaches a second pressure threshold, after a certain period of time haspassed, or after a diverter of a valve reaches a closing angle.

In the illustrated example, the fluidics subsystem 110 has a cassettebody 301 that may be accommodated by the surgical console 100 as asurgical cassette. The fluidics subsystem 110 includes an irrigationsystem 300 and an aspiration system 305, which are controlled by acomputer 103 such as a controller 360. The irrigation system 300 andaspiration system 305 are in fluid communication with the handpiece 112.Parts that are in fluid communication with each other are parts forwhich fluid is allowed to flow between (to and/or from) the parts.

Console 100 may include one or more handpieces 112, including anultrasonically-driven phaco handpiece, a laser handpiece, and/or othersuitable handpiece. In certain embodiments, the handpiece 112 may be anultrasonically-driven phaco handpiece. In the illustrated example, thephaco handpiece 112 includes an irrigating part 320, a cutting needle355, and a handpiece pressure sensor (HPS) 365. The irrigating part 320provides fluid to the surgical site, and may be an irrigating tip or anirrigating sleeve that surrounds the needle 355. The cutting needle 355is a hollow needle that vibrates at a fixed frequency to break uptissue. Fluid and tissue may be aspirated through the needle 355.

In certain embodiments, the handpiece 112 may be a laser handpiece. Alaser handpiece uses laser energy to fragment the lens to facilitate thephacoemulsification process. In the embodiments, the fluidics subsystem110 supports the laser handpiece (e.g., provides irrigation andaspiration functions) in a manner similar to that of a phaco handpiece.In certain embodiments, the laser handpiece may include a sensor thatmeasures the surgical site pressure to provide a measurement forpost-occlusion mitigation.

The HPS 365 is an irrigation pressure sensor that detects the irrigationpressure within the irrigation conduit 302. In the illustrated example,the HPS 365 is located on the handpiece 112 close to the surgical site,e.g., less than 12 inches from the surgical site. The proximity to thesurgical site may enable quick detection of changes in pressure (as mayoccur during an occlusion break) and allow for real-time surgesuppression. In some examples, HPS 365 detects pressure changes within50 milliseconds of an occlusion break, which may enable the controller360 to respond to pressure deviations before IOP is overly negativelyaffected. In general, an irrigation pressure sensor may be located atany suitable location, such as any suitable location of the handpiece112 (e.g., the proximal end, the distal end, or proximate the irrigatingpart 320), at any suitable location along an irrigation conduit, or atany suitable component in fluid communication with the surgical site(e.g., within in a separate tube or probe).

The aspiration system 305 carries fluid away from the surgical sitetowards a drain reservoir 340 by creating and maintaining a vacuumpressure (or negative pressure) in aspiration conduits 303. Vacuumpressure can be described as negative pressure. Accordingly, increasingthe vacuum pressure may be described as increasing negative pressure ordecreasing pressure, and decreasing the vacuum pressure may be describedas decreasing negative pressure or increasing pressure.

The aspiration system 305 includes an aspiration conduit 303, a valve337, a reservoir 333, a pressure-vacuum source 336, an aspirationpressure sensor (APS) 330, an aspiration pump 335, and a drain reservoir340 in fluid communication along aspiration paths as shown. Theaspiration conduit 303 provides fluid communication between theaspiration system 305 and the handpiece 112. In the illustrated example,the aspiration conduit 303 aspirates from the needle 355 of thehandpiece 112. The reservoir 333 stores fluid that may be used for surgemitigation. Pressure-vacuum source 336 maintains and adjusts thereservoir pressure of reservoir 333. For surge mitigation, the reservoirpressure may be in the range of 0 to 500 mmHg (e.g., a value in therange of 0 to 100, 100 to 400, or 400 to 500 mmHg). Examples of thereservoir 333 include a venturi, drain, vent, irrigation, and othersuitable reservoir, and the reservoir 333 may be implemented as one ormore reservoirs.

The valve 337 controls flow to and/or from the reservoir 333 for thehandpiece 112. Valve 337 controls the vacuum pressure within theaspiration conduit 303 by opening and/or closing channels in order tomitigate the effects of a post-occlusion surge. Examples of the valve337 include a vent, drain, rotary, variable vacuum relief, and othersuitable valve, and the valve 337 may be implemented as one or morevalves. The valve 337 may be located at any suitable location of thefluidics subsystem 110. For example, the valve 337 may be located closerto the eye, e.g., proximate to an aspiration connector, which mayimprove mitigation performance. As another example, the valve 337 may belocated at the reservoir 333 or along the aspiration conduit 303 betweenan aspiration connector and the reservoir 333. Valve operations aredescribed in more detail with reference to FIGS. 4A to 4F.

APS 330 detects the aspiration pressure within aspiration conduit 303.The aspiration pump 335 creates a vacuum pressure within the aspirationconduit 303 between the pump 335 and the eye to draw fluid from thesurgical site and into the drain reservoir 340. The pump 335 may be,e.g., a dual segment elastomer pump. The drain reservoir 340 receivesthe fluid from the surgical site. Drain reservoir 340 may be a bag or anintersection of conduits that receives fluid within the cassette body301.

The controller 360 is a computer that controls parts of the fluidicssubsystem 110, such as valves (e.g., 337) and pumps (e.g., 335), inresponse to pressure sensors (e.g., 330, 365, a sensor at or inside ofthe eye) to control pressure within conduits 302, 303 in order tomaintain a target pressure at the surgical site. In certain embodiments,the controller 360 controls the valve 337 to mitigate a post-occlusionsurge. In the embodiments, the computer 103 controls the valve 337 todecrease the vacuum pressure in an aspiration conduit when the surgicalsite pressure is less than the first pressure threshold, and controlsthe valve to cease decreasing the vacuum pressure when the surgical sitepressure the reaches a second pressure threshold, after a certain periodof time has passed, or after a diverter of a valve reaches a closingangle.

The controller 360 may open and/or close channels of the valve 337 toadjust the vacuum pressure in the aspiration conduit 303. A channel isopened by making the passageway of the channel larger. A channel that isopened to allow for maximum fluid flow is fully opened; otherwise, thechannel is partially opened. A channel is closed by making thepassageway of the channel smaller. A channel that is closed such that nofluid passed through is fully closed; otherwise, channel is partiallyclosed.

In some embodiments, the controller 360 regulates the amount that achannel is opened or closed (i.e., the size of the passageway of thechannel) based on the deviation between the detected pressure and atarget pressure. For example, for a larger deviation, the passageway maybe larger to allow more fluid. For a smaller deviation, the passagewaymay be smaller to allow less fluid. In these examples, as a detectedpressure reaches a target pressure, the deviation decreases, so thepassageway may be made smaller.

In certain embodiments, the controller 360 may have access to a memorythat stores one or more pressure thresholds, and may perform an actionin response to a detected pressure reaching a pressure threshold. Forexample, when a detected pressure reaches a pressure threshold, thecontroller 360 controls a valve to adjust the pressure. In certainembodiments, a first pressure threshold may indicate that the pressureassociated with the surgical site has rapidly decreased to anunacceptable level, such as in response to an occlusion break. Inresponse, the controller 360 decreases the vacuum pressure in theaspiration conduit 303 to mitigate the rapid decrease of the surgicalsite pressure. A second pressure threshold may indicate that thesurgical site pressure has recovered. In response, the controller 360ceases decreasing the vacuum pressure in the aspiration conduit 303.

The controller may determine the surgical site pressure from one or moresuitable sensors. In certain embodiments, a decrease in irrigationpressure may indicate a drop in the surgical site pressure in responseto, e.g., an occlusion break. In the illustrated example, one or moreirrigation pressure sensors (e.g., HPS 365) detect the irrigationpressure within the irrigation conduit 302. The first pressure thresholdmay define the irrigation pressure at which the controller 360 shoulddecrease the vacuum pressure, and may have any suitable value, e.g., avalue in the range of 0 to 207 mmHg (e.g., a value in the range of 0 to35, 35 to 100, or 100 to 207 mmHg).

In certain embodiments, an aspiration pressure may indicate when anacceptable surgical site pressure has been reached in response tomitigating the post-occlusion surge. In the illustrated example, theaspiration pressure sensor 330 detects the aspiration pressure. Thesecond pressure threshold may define the aspiration pressure at whichthe controller 360 should stop decreasing the vacuum pressure, and mayhave any suitable value, e.g., a value in the range of 0 to 760 mmHg(e.g., a value in the range of 0 to 30, 30 to 300, or 300 to 760 mmHg).In some embodiments, the second pressure threshold may be selected suchthat the controller 360 stops decreasing the vacuum pressure before thetarget IOP range is reached, since the vacuum pressure typicallycontinues to decrease for a short while after the controller 360 acts tostop the decrease.

While the above example uses a first pressure threshold defined in termsof an irrigation pressure and a second pressure threshold defined interms of an aspiration pressure, the first and second thresholds may bedefined in terms of use suitable type of pressure (e.g., aspirationpressure, an irrigation pressure, or an intraocular pressure) from anysuitable sensors that indicate the pressure at the surgical site. Inaddition, the first and/or second thresholds can be defined in terms ofthe same or different types of pressure, e.g., both thresholds could bedefined in terms of an aspiration pressure.

FIGS. 4A through 4F illustrate examples of operations a valve, such asthe valve 337, may be controlled to perform. In certain embodiments, acontroller may move a diverter to an opening angle to open a channel ofa rotary valve. As fluid flows through the channel and pressure isreduced, the diverter may move in the opposite direction. When thediverter reaches a closing angle indicating reduction to a desiredpressure, the controller may close the channel. The opening and closingangles may be selected based on the operation of the particular valve ina particular fluidics subsystem 110, in particular the pressuresachieved when the diverter is at particular angles in a particularfluidics subsystem 110. These angles may be determined by operating thediverter at different angles in the fluidics subsystem 110 and notingthe resulting pressures.

(1) Venting of Reservoir. During venting (e.g., for surge mitigation), achannel from the reservoir 333 to the aspiration pump 335 and/or achannel from the reservoir 333 to an aspiration connector may be opened.FIG. 4A shows a channel from the reservoir 333 via a reservoir passage390 to the aspiration pump 335 via a pump passage 392, and a channelfrom the reservoir 333 via the reservoir passage 390 to the aspirationconnector via an aspiration connector passage 394, for dual venting.FIG. 4B shows a channel from the reservoir 333 via reservoir passage 390to the aspiration pump 335 via the pump passage 392, for reservoirdraining or for reservoir driven reflux to suction path. FIG. 4C shows achannel from the reservoir 333 via reservoir passage 390 to theaspiration connector via the aspiration connector passage 394, foraspiration or for reservoir driven reflux.

The selection of channels to open may be made according to any suitablefactors. For example, if there is a large deviation between the detectedpressure and the pressure threshold, both channels may be opened toincrease flow and more rapidly vent the stored vacuum. A large deviationmay have a value between, e.g., 0 to 35 mmHg (e.g., a value in the rangeof 0 to 10, 10 to 20, or 20 to 35 mmHg).

(2) Reservoir Maintenance. In one example of maintaining a fluid levelin the reservoir 333, channels from the aspiration connector to thereservoir 333 and from the reservoir 333 to the aspiration pump 335 maybe opened, such that the valve 337 supports different flows withdifferent channels. The pressure-vacuum source 336 may enable a vacuumin the reservoir 333 to facilitate the flow from the aspirationconnector. FIG. 4D shows a channel from the aspiration connector via theaspiration connector passage 394 to the reservoir 333 via reservoirpassage 390, and a channel from the reservoir 333 via reservoir passage390 to the aspiration pump 335 via the pump passage 392, for reservoirdriven aspiration with drain pumping.

(3) Aspiration Pump-Connector Channels. A channel between an aspirationconnector and aspiration pump 335 (e.g., from the aspiration connectorto aspiration pump 335 and/or from aspiration pump 335 to the aspirationconnector) may be opened. FIG. 4E shows a channel from the aspirationconnector via the aspiration connector passage 394 to the aspirationpump 335 via the pump passage 392, for aspiration driven directly bypumping. FIG. 4F shows a channel from the aspiration pump 335 via thepump passage 392 to the aspiration connector via the aspirationconnector passage 394, for pump driven reflux. In certain embodiments,to prevent fluid from entering or exiting reservoir 333, any channel toreservoir 333 may be closed and/or the pressure-vacuum source 336 may bedisabled.

FIGS. 5A through 5F illustrate examples of operations a valve 337 a thatmay be controlled to perform the operations of the valve of FIGS. 4Athrough 4F, respectively. The valve 337 a may be any suitable valve,e.g., a single channel valve that can provide dual paths.

FIG. 6 illustrates an example of a method 410 that may be used by thefluidics subsystem 110 of FIG. 3 to mitigate a post-occlusion surge. Themethod starts at step 412, where the controller 360 monitors a pressureassociated with the surgical site. The controller 360 may use anysuitable sensor to measure the surgical site pressure at steps 412 and418, e.g., a sensor of the fluidics subsystem 110 or a sensor at orinside of the eye that directly measures IOP of the eye. In certainexamples, the controller 360 may use an irrigation sensor (e.g., HPS365) to measure irrigation pressure as the surgical site pressure. Thecontroller 360 determines whether the surgical site pressure hasdecreased below a first pressure threshold at step 414, indicating that,e.g., an occlusion break has occurred. If there is no such decrease, themethod returns to step 412, where the controller 360 continues tomonitor the surgical site pressure. If there is such a decrease, themethod proceeds to step 416.

The controller 360 reduces the vacuum pressure at step 416 to initiatereturning the surgical site pressure to a target range. In certainexamples, the controller 360 may reduce the vacuum pressure by openingone or more channels of the valve 337 to allow fluid to flow from thereservoir 333 to the aspiration conduit 303. The controller 360 monitorsthe surgical site pressure at step 418. In certain examples, thecontroller 360 may measure the aspiration pressure using an aspirationpressure sensor 330 as the surgical site pressure.

At step 420, the controller 360 determines whether the surgical sitepressure has reached (e.g., is equal to or greater than) a secondpressure threshold. If the surgical site pressure has not reached thesecond pressure threshold, then the method returns to step 418 tocontinue to monitor the surgical site pressure. If the surgical sitepressure has reached the second pressure threshold, then the methodproceeds to step 422, where the controller ceases reducing the vacuumpressure at step 410. In certain examples, the controller 360 closes theone or more channels to cease reducing the vacuum pressure. The methodfor mitigating a post-occlusion surge then ends.

FIG. 7 illustrates another example of a method 510 that may be used bythe fluidics subsystem 110 of FIG. 3 to mitigate a post-occlusion surge.Steps 512 and 514 are analogous to steps 412 and 414 of FIG. 5.

In certain embodiments, the fluidics subsystem 110 performs steps 516 aand 518 a, and in other embodiments, the fluidics subsystem 110 performssteps 516 b and 518 b. In certain embodiments, at step 516 a, thecontroller 360 opens one or more channels of the valve 337 to allowfluid to flow in order to reduce the vacuum pressure. The controller 360closes the one or more channels at step 518 a after a predeterminedperiod of time. The predetermined period of time may have any suitablevalue, e.g., a value between 1 millisecond and 10 seconds.

In other embodiments, at step 516 b, the controller 360 moves a diverterof the valve 337 in the rotation direction to an opening angle to openone or more channels to allow fluid to flow in order to reduce thevacuum pressure. As the pressure reduces, the diverter moves in theopposite direction. The controller 360 closes the one or more channelsat step 518 b after the diverter reaches a closing angle. The openingand closing angles may be selected based on the operation of theparticular valve 337 in a particular fluidics subsystem 110,specifically, based on the pressures achieved when the diverter is atparticular angles in the fluidics subsystem 110.

The controller 360 waits for a waiting period before continuing withnormal operation at step 520. The waiting period allows for the fluidicssubsystem 110 to normalize after the occlusion break. The waiting periodmay have any suitable value, e.g., a value less than 10 seconds. Themethod for mitigating a post-occlusion surge then ends.

A component (such as the computer 103 or controller 360) of the systemsand apparatuses disclosed herein may include an interface, logic, and/ormemory, any of which may include hardware and/or software. An interfacecan receive input to the component, send output from the component,and/or process the input and/or output. Logic can perform operations ofthe component. Logic may include one or more electronic devices thatprocess data, e.g., execute instructions to generate output from input.Examples of such an electronic device include a computer, processor ormicroprocessor (e.g., a Central Processing Unit (CPU), and computerchip. Logic may include computer software that encodes instructionscapable of being executed by the electronic device to performoperations. Examples of computer software includes a computer program,an application, and an operating system.

A memory can store information and may comprise tangible,computer-readable, and/or computer-executable storage medium. Examplesof memory include computer memory (e.g., Random Access Memory (RAM) orRead Only Memory (ROM)), mass storage media (e.g., a hard disk),removable storage media (e.g., a Compact Disk (CD) or Digital Video orVersatile Disk (DVD)), database and/or network storage (e.g., a server),and/or other computer-readable media. Particular embodiments may bedirected to memory encoded with computer software.

Although this disclosure has been described in terms of certainembodiments, modifications (such as changes, substitutions, additions,omissions, and/or other modifications) of the embodiments will beapparent to those skilled in the art. Accordingly, modifications may bemade to the embodiments without departing from the scope of theinvention. For example, modifications may be made to the systems andapparatuses disclosed herein. The components of the systems andapparatuses may be integrated or separated, or the operations of thesystems and apparatuses may be performed by more, fewer, or othercomponents. As another example, modifications may be made to the methodsdisclosed herein. The methods may include more, fewer, or other steps,and the steps may be performed in any suitable order.

To aid the Patent Office and readers in interpreting the claims,Applicants wish to note that they do not intend any of the claims orclaim elements to invoke 35 U.S.C. §112(f) unless the words “means for”or “step for” are explicitly used in the particular claim. Use of anyother term (e.g., “mechanism,” “module,” “device,” “unit,” “component,”“element,” “member,” “apparatus,” “machine,” “system,” “processor,” or“controller”) within a claim is understood by the applicants to refer tostructures known to those skilled in the relevant art and is notintended to invoke 35 U.S.C. §112(f).

What is claimed:
 1. An ophthalmic surgical system, comprising: anirrigation conduit in fluid communication with a handpiece andconfigured to carry fluid toward a surgical site; an aspiration conduitin fluid communication with the handpiece and configured to carry fluidaway from the surgical site; an aspiration pump configured to create avacuum pressure in the aspiration conduit to draw fluid through theaspiration conduit towards a drain reservoir; a reservoir configured tohold fluid and to be coupled with a pressure-vacuum source to manage areservoir pressure of the reservoir; a valve in fluid communication withthe aspiration conduit and the reservoir, the valve configured toprovide one or more channels between the aspiration conduit and thereservoir; a first pressure sensor configured to detect a pressureassociated with the surgical site; and a computer configured to controlthe valve in response to the pressure detected by the one or morepressure sensors to mitigate a pressure change or a volume change. 2.The system of claim 1, the computer further configured to: control thevalve to decrease the vacuum pressure in the aspiration conduit when thepressure associated with the surgical site is less than a first pressurethreshold.
 3. The system of claim 2, the computer further configured to:control the valve to decrease the vacuum pressure by controlling thevalve to provide the one or more channels to allow fluid from thereservoir to the aspiration conduit.
 4. The system of claim 3, thecomputer further configured to: control the valve to provide the one ormore channels by providing a first channel from the reservoir to theaspiration pump or a second channel from the reservoir to an aspirationconnector, the aspiration connector configured to couple to thehandpiece.
 5. The system of claim 3, the computer further configured to:control the valve to provide the one or more channels by providing afirst channel from the reservoir to the aspiration pump and a secondchannel from the reservoir to an aspiration connector, the aspirationconnector configured to couple to the handpiece.
 6. The system of claim2, the first pressure threshold having a value in the range of 0 to 207mmHg.
 7. The system of claim 2 wherein the first pressure sensor detectswhen the pressure associated with the surgical site is less than thefirst pressure threshold.
 8. The surgical cassette of claim 7, the firstpressure sensor comprising an irrigation pressure sensor configured todetect an irrigation pressure within the irrigation conduit.
 9. Thesurgical cassette of claim 7, the first pressure sensor comprising anirrigation pressure sensor configured to detect an irrigation pressureat the surgical site.
 10. The surgical cassette of claim 7, the firstpressure sensor located at the handpiece.
 11. The surgical cassette ofclaim 2, the computer further configured to: control the valve to ceasethe decrease of the vacuum pressure in the aspiration conduit bycontrolling the valve to cease allowing the fluid after a predeterminedperiod of time.
 12. The surgical cassette of claim 2, the computerfurther configured to: control the valve to cease the decrease of thevacuum pressure in the aspiration conduit by controlling the valve tocease allowing the fluid when a diverter of the valve reaches a closingangle.
 13. The surgical cassette of claim 2, the computer furtherconfigured to: control the valve to cease the decrease of the vacuumpressure in the aspiration conduit when the pressure associated with thesurgical site reaches a second pressure threshold by controlling thevalve to cease allowing the fluid.
 14. The surgical cassette of claim13, the second pressure threshold having a value in the range of 0 to760 mmHg.
 15. The surgical cassette of claim 13 further comprising asecond pressure sensor, the second pressure sensor detects when thepressure associated with the surgical site reaches the second pressurethreshold.
 16. The surgical cassette of claim 15, the second pressuresensor comprising an aspiration pressure sensor configured to detect anaspiration pressure within the aspiration conduit.
 17. The surgicalcassette of claim 1, the pressure-vacuum source configured to maintainthe reservoir pressure of the reservoir at a specific pressure with avalue in the range of 0 to 500 mmHg.
 18. The surgical cassette of claim1, the valve located at the reservoir.
 19. The surgical cassette ofclaim 1, the valve located along the aspiration conduit and between anaspiration connector and the reservoir, the aspiration connectorconfigured to couple to the handpiece.